Reproducer



Jan. 9, 1940.

|.. B. coRNwELL REPRODUCER I Filed April 17', 1936 INVENTOR I Lionel B. Uwnwelb BY ATTORNEYS (S Mob,

Patented Jan. 9,- 1 940 v .Lionel B. coin well, Tean eck, N. -J.,f assignor to Cinaudagraph Corporation, a corporation of I Delaware 1 Application April 17,, 1936, Serial no. 74,933

' 2 Claims. (o1-.1'z9-115.5)

This invention relates to sound reproducers, and particularly those of the loud speaker type. The object of the invention is to provide a speaker which is simplein structure and durable 5 in use, and which will maintain close adjustment and accurate alinement of the-relatively movable parts. I

Further objects of the invention, particularly in the relative'supporting structure and guidance of the parts will appear from thefollowing description taken inconnection with the accompanying drawing in which Fig. -l is a vertical sectional view of a loud speaker embodying the invention,

'Fig. 2 is, a face view Fig. l, and r Fig.3 is aaplanview of the. centering net structure of the diaphragm shown in Fig. 1.

Referring to Figs. 1 and'2, a rear spider or flange ring H supporting the front bridge piece {2 by rivetsl3.- A magnet structure M-is-fastened to the bridge l2 by bolts I4 and screw I5, the permanent magnet structure comprising magnet l6,'core l1 and pole pieces l8, IS with a narrow annular air gap Zllfor the voice coil V of the reproducing diaphragm or cone C.

The diaphragmC is preferably formed of a a continuous sheet of fibrous material of double 3o, conical formation and at its periphery is shaped to provide the radial flange 22 cemented to the 'fiange ring I! and with the corrugations 23 just within this peripheral-portion. The outer cone 24 and the inner cone 25 of the diaphragm are oppositely directed and meet in the ridge 26, and the inner edge of the inner cone is formed with of the speaker shown to the post 35. hese: 36 .will have its strands ably. be impregnated with a hardening compound imparting rigidity while maintaining lightness.

The post 35 isLin formnof a dowel riveted to the "interlocked at the intersections and will preferchassis I0 at the center thereof and snugly fitting in the bore 31 or core 11. Care is taken to have thi's'bore concentric with the air gap G'and to have the voice coil V. concentric with the dowel 35, the combination insuring accurate alinement I 20 chassis H3 carries at its periphery the annular r.

'l of the voice coil in the air gap. 'As shown in Fig.

l the screw l5 of the magnet assembly threads into the end of -the dowel 35and draws it tightly against the shoulder at the inner end of bore 31. -j The front bridge and housing are thus joined tightly at theperiphery and at the center, giving double support of each and cooperating to maintain precise relative spacing. The diaphragm C is also supported bothat its periphery and. by the centering. net 36, and is free for axial vibration while held securelypagainst radial shifting.

The. chassis Ill (Fig. 1) "is of the'spider type with open's'paces between the periphery and cen- 'ter'and the sound from diaphragm Cis projected both 'frontwa'rd (towardv the right Fig. 1) and rearward (toward the left Fig. 1). The structural combination of Figs. 1 and 2 gives a very an annular V groove 27 and then carriedinward in a dome formation 28 with-a center opening providing clearance around post 35. The voice 4 coil cylinder 29, preferably of mica, is seated and cemented in the groove 21 and at its other end carries the voice coil V.

- Thechanneled formation provided by the join- I ing of the opposite cones 24,125 greatly contributes to the rigidity of the central portion 'of the diaphragm and the resulting'crest 26 also serves as a connecting ring for the centering supporting means precisely alining'the voice coil Vin the air gap. This centering means stretches 2S and may be a stamped out unit of sheet material or composed of radial strands, or'preierably is of open net formation 36' (Fig. 3) in ciracross from a center post 01' pin 35 to theridge cular formation having its periphery cemented to the ridge 2B and its center fastened securely compact loud speaker. The r'e-entrant diaphragmC accommodates location of the voice coil -V and its magnet M inside of the conical formation, making the overall depth very slight as compared to conventional speakers. The'conical housing In of drawn metal, preferably steel,

constitutes a protecting rigi-difying cover for'the diaphragm andserves as a rigid attachment.

around the periphery as well as an anchorage. for the bridge strap l2. .At the concave. center disk l0 the construction provides alstifi hold forthe riveted connectionand the brass dowel pin riveted to .the housing IDholds the centering net.

This centering net is a flat 1 36 firmly in place.

disk of flexible materialfull of holes allowing the high frequency-vibrations to pass through it, and

' at the same time'permitting ample axial travel forlthe production of low notes while maintain ing the voice coil Vin'perfect alinement in the air gap between the magnet poles. Another advantage of the structure shown in Fig. l is the separation between the magnet M and the steel housing lily This is importantfbecause the lines of flux of the magnet will tend to leak into an y paths of magnetic material tooclose or'in contact with it with a consequent tendency to reduce-the flux densityin the air gap. The dowel 35 and bridge piece [2 are of brass or other nonmagnetic material and with the spacing of the steel housing III as shown the flux density of the air gap is preserved.

' I claim:

1. In a loud speaker construction the combination with a frame member having anannular periphery, of a cooperating bridge member extending across from one side to the other of said periphery, axial means connecting said bridge to said frame at the center, a magnet unit supported by said bridge and a diaphragm connected to the frame periphery and carrying a; voice coil cooperating with said magnet unit,

said diaphragm being apertured to fit said axial means.

2. In a loud speaker construction the combination with a frame member having an annular periphery, of a cooperating bridge member extending across from one side to the other of said periphery, axial means connecting said bridge to said frame at the center, a magnet unit supported by said bridge, a diaphragm connected to the frame periphery and carrying a voice coil cooperating with said magnet unit, said diaphragm being apertured to fit said axial means,

and a centering net carried by said central axial connection and having its periphery attached to said diaphragm.

LIONEL B. COR-NWELL. 

